SB 

94-5 



COTTOH WORJJ OP. "CATERPILLAR" 

By 
Warren Elmer Hinds. 




Book , C ; ^ 5 K 5 . 



62d Congress \ 
2d Session j 



HOUSE OF REPRESENTATIVES 



i Document 
'I No. 917 



BULLETIN No. 164, ALABAMA AGRICULTURAL EXPERIMENT STATION 
OF THE ALABAMA POLYTECHNIC INSTITUTE, AUBURN. ALA. 



Cotton Worm or "Caterpillar" 



BY 



,r .^ 



WrE. HINDS /?7(o 

ENTOMOLOGIST 



ISSUED AUGUST 1, 1912 




WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1912 



Committee of Trustees on Experiment Station, 



Hon. R. F. Kolb, Montgomery. 
Hon. H. L. Martin. Ozark. 
Hon. a. W. Bell, Annistou. 

Station Staff. 






C. C. Thach, president of the college. 
J. F. DuGGAR, director of station. 

DBa-ARTMENTAL ORGANIZATION. 
AGRICULTURE. 



J. F. Duggar, agriculturist. 
E. F. Cauthen, associate. 
M. F. Funchess, assistant. 
J. T. Willinmson, field agent. 



C. A. Gary, veterinarian. 
I. S. McAdory. assistant. 



L. J. Hawley, field agent. 
J. F. Duggar, jr.. assistant. 
O. H. Sellers, secretary. 



VETERINARY. 



W. M. Howell, assistant. 
I*. B. Whitsell. assistant. 



CHEMISTRY. 



B. B. Ross, chemist, State chemist. 

J. T. Anderson, chemist, soil and crops. 

C. L. Hare, physiological chemist. 



T. Bragg, first assistant. 
S. Adler, assistant. 



li. N. Duncan, superintendent.* 
J. B. Hobdy, assistant.* 



F. E. Lloyd, botanist. 



P. F. Williams, horticulturist. 
J* C. C. Price, assistant. 



W. E. Hinds, entomologist. 
W. F. Turner, assistant. 



EXTENSION. 

S. I. Bechdel. assistant.' 
J. M. Moore, assistant.* 

BOTANY. 

C. S. Ridgway, assistant. 

HORTICULl-URE. 

H. M. Conolly, field agent. 

ENTOMOLOGY. 

J. A. Dew. field agent. 



PLANT PATHOLOGY. 

F. A. Wolf, pathologist. 

ANIMAL INDUSTRY. 

Dan T. Gray, animal husbandman. T.. W. Shook, assistant.* 

W. F. Ward, junior animal husband- S, S. Jordan, assistant.' 

man.* A. R. Gissendanner, assistant. 

L. W. Summers, assistant. C. D. Allis, assistant. 



i In cooperation with United States Department of Agriculture. 



D. OF D. 
APR 13 :I913 



^ 



THE COTTON AVORM OR CATERPILLAR. 

(AhilKiniti (irfiillacca, liiibii.) 
By W. E. Hinds. 

The name " army Avorm " is also often applied to this sj^ecies, as 
it is to several others, among which the " grass worm " or " fall army 
worm " of the South is the most common. The distinction between 
these two species should be kept clearly in mind by the reader, as 
the two species have quite different habits as to the plants upon which 
they feed, the general manner of their feeding, and in their manner 
of transformation from the caterpillar to the moth stage. AYe are 
here considering only the cotton worm, which feeds upon nothing but 
cotton and which species has repeatedly done extensive damage to 
cotton throughout the South during more than a century. 

The cotton worm is not a native insect in the United States, as cot- 
ton itself is not native here. It comes to us each year that it occurs 
in the cotton belt from the 3Vest Indies and from Central and South 
America, where cotton grows wild from year to year. The first 
serious outbreak on record occurred as far back as 1793 in Georgia 
and South Carolina. Since then cotton worms have been found 
irregularly, without doubt being dependent upon a certain coincident 
set of either favorable or unfavorable climatic and food conditions 
in its winter home as well as here. 

During this 119 years there have been seven great caterpillar years, 
of which 1911 was the last. In Alabama, and perhaps throughout the 
South, 1873 will be long remembered as marking the climax of a 
series of three years of increasing damage. Yet in that year but 38 
counties in this State reported trouble from worms. In the outbreak 
of 1911 before the end of the season 66 of the 68 counties in Alabama 
had been practically stripped by the worms. Careful field studies 
combined with reports received from all counties indicated that Ala- 
bama alone suffered a reduction of between 120,000 and 175,000 bales. 
This lint, with its seed, would mean at the minimum figure a damage 
of more than $7,000,000 in this one State. Similar injury occurred in 
Mississippi, Arkansas, Louisiana, and Texas. The severity of the 
injury is hidden to a large extent by the record-breaking crop pro- 
ducecl in spite of it, and was greatly decreased from what was antici- 
pated because of the unusual proportion of the crop of 1911 that was 
" made '" before the end of July. Yery little cotton was added to 
the crop after that. 

In the fight against the worms in 1911 it is certain that more arsen- 
ical poison was used than has ever been used elsewhere in anything like 
the same area and in the same space of time. Powdered arsenate of 
lead was used for the first time against the cotton worm and easily 



4 • COTTON WORM OR CATERPILLAR. 

proved its many advantages over Paris green for this pnrpose. Dur- 
ing the first season much more of it was nsed than tliere was of Paris 
green. In Alabama and Mississippi alone more than 1,000,000 pounds 
of these two poisons Avas distributed, and the value of this item in the 
making of the 1911 crop was, therefore, all of $250,000. Had the 
poison been available and planters generally ready and willing to use 
it promptly and properly a very large part of the loss estimated 
above for Alabama could have been prevented. 

CONDITIONS INDICATING OUTBREAKS. 

A study of the history of cotton-worm outbreaks shows that in the 
years of greatest damage certain conditions have always occurred. 
Among the most significant of these have been unusually wet seasons, 
which both favored the development of the worms arid retarded that 
of the crop. Cotton was late, or at least in thrifty, vigorous leaf, 
and the worms first appeared scatteringly before the middle of 
August in the Middle Gulf States. A condition of frequent showers 
and of many cloudy days during August and September has increased 
the outbreak. The generations or '"'■ crops " of worms are completed in 
between three and four weeks with constantly increasing numbers of 
the worms and their more general distribution. There are then cer- 
tain to be three generations of worms before the cotton can be picked 
out. Whenever these conditions are present we may anticipate a 
serious outbreak of the worms. It is true that subsequent conditions 
unfavorable to the worms, such as extremely hot, dry weather, may 
sers'e to check the outbreak materiall}^, but they are not likely to pre- 
vent material damage. 

LIFE HISTORY. 

The full life history of the cotton worm may be more easily and 
closely followed by the average man than can that of almost any other 
insect. All of its four stages are to be found on the cotton plant, all 
above groimd, and frequently all stages may be j^resent at the same 
time. Three of these stages do no damage whatever to the plant. 

Fi7'st stage: The ec/g. — The Qgg laid by the cotton-worm moth, or 
" candle fly," is of a pale bluish-green color, gradually becoming more 
nearly white as it approaches hatching time. It is only about one- 
fortieth of an inch in diameter, but a very pretty shell-like object, 
that can be found only by rather careful hunting on the undersides 
of the larger leaves around the middle third of the cotton plant. 
They are not at all hard to see when one becomes accustomed to 
them. They are always placed singly, although several may occur 
on one leaf. (See PI. I, fig. 1.) The Qg^ hatches in two or three days 
during warm weather, as in August, but requires a little longer time 
later in the season. 

Second stage: The cotton worm. — The caterpillar is the only stage 
that really injures cotton. On hatching from the eggs the worms are 
pale yellowish-green in color and very inconspicuous. They are 
found only on the undersides of the leaves on which the eggs were 
laid. As they grow the markings become more distinct and fre- 
quently vary widely, showing an increase in the proportion of black 
especially. P'ully grown cotton worms are very conspicuously 



COTTON WOEM OR CATERPILLAR. 



marked, and it would seem that once seen abundantly they might 
always be remembered. They are rather slender and reach a length 
of about 1| inches. The caterpillars of the earlier generations usu- 









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1 1.: -^i u-^A 



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'.^isSSltSm 



fli • ' 1^ 





21 




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Plate I.— COTTON WORM STAGES. 

Pig. 1, the egg; lig. 2, moth, natural position; fig. :>. moth showing markings on upper 
and under sides of wings ; fig. 4, worms showing variations in color ; fig. 5, transformation 
to pupa. Fig. 1, enlarged x 10; fig. 2. enlarged x 2; others natural size. (Original.) 



6 COTTON WORM OR CATERPILLAR. 

ally show iiiucli less black than do those of a later period near the 
end of the season. The lif^lit forms are quite brii>ht yellowish-green 
in body color, with three narrow white stripes and two rows of con- 
spicuous black spots, each set with a black spine, arranged along its 
back. In these the black sjiot is surrounded by a circle of white color. 
(PI. II, fig. 1.) The dark-colored specimens are due to the increase 
of black between the white stripes and including the rows of black 
spots which appear in the lighter worms until it forms velvety black 
stripes with only veiy narrow white stripes between. The hind pair 
of legs in the cotton worm stand out very prominently as they rest 
upon the cotton leaves. "When the worms travel they go with a half- 
looping movement that is quite characteristic of this species. The 
skin is shed five times in the growth of each worm. The worms are 
very active, and have a peculiar method of protection by jumping 
quickly to a distance of a foot or two horizontally when disturbed. 
They may catch upon some other plant in the next row. This whole 
growth may occur in from 10 to 15 days usually. 

As soon as the growth is complete the worms draw together parts 
of leaves so as to cover their bodies and spin a very loose silken 
cocoon, within which they transform to the moth stage. In the 
TTnited States these worms have never been known to develop com- 
pletel}^ on any plant but cotton. 

Third stage: The pvpa. — The beginning of this stage is known to 
everyone as " webbing up." Within the web the caterpillar changes 
first \through the steps plainly shown in Plate I, figure 5, to the fa- 
miliar brown conical body that is known by nearly eveiy cotton 
planter. This always occurs on some plant above the ground, but 
may be on any weed or grass that can give them the protection de- 
sired. This is one respect in which this species differs entirely from 
the cotton-boll worm and the grass worm or fall army worm, both 
of which burrow into the ground for protection while they are trans- 
forming and never go through this change on the fflant. After a 
week or a little longer in this stage the moths are ready to emerge 
and they complete the generation. 

Four'fk sfaf/e: The m-oth. — Cotton-worm moths or " candle flies," as 
they are often called, are of the size and general appearance shown in 
Plate I, figure 3, and enlarged in figure 2. The general color is quite 
uniform olive-brown, but may vary somewhat. It is frequently a 
dark tan, sometimes with a purplish tinge. There is a rather distinct, 
small gray or black spot near the middle of each front wing and 
faint, irregvdar or wavy dark, reddish cross lines shown on the front 
wings. The outer edge of each wing has a narrow white fringe with 
dark spots on the front pair. The posit i(m Avhen at rest is shown best 
in Plate I. figure 2. The moths hide by day among the cotton, and 
especially around grassy spots. They fly, feed, and lay their eggs at 
night. When disturbed they move with a peculiar SAvift, darting 
flight and hide again so quickly that they are hard to capture by 
iiand. As with many other moths, they are strongly attracted to 
lights, and during outbreaks frequently make it impossible for one to 
read or work with a lamp in an unscreened house. These moths feed 
somewhat on nectar produced by many plants, especially by the leaf 
glands of cotton, and also upon the juices of fruits, which they can 
wound with their slender tongue when it is uncoiled. The moth stage 



COTTON WORM OR CATERPILLAR. 7 

completes the life cycle and the females begin very soon the deposition 
of eggs for the next generation. 

Within a. week or 10 days they may deposit fi^om 400 to COO 
eggs and then die, but their powers of flight are such that at the 
time of their death they ma}^ be man}^ hundreds of miles from wliere 
they hatched out. A remarkable demonstration of their flight 
occurred in September, 1911, when store fronts and electric-light 
poles in Cleveland, Ohio, were thickly covered with moths of this 
species. They were very numerous also in New Jersey, New York, 
and Massachusetts, and were taken also in Maine and Canada. But 
in all this northern countiw there is no food plant for the species and 
all must perish. The instinct for northward flight has carried them 
too far. 

Ilihcrnathm. — AVhat has just been said regarding the flight of 
these moths will help us to understand better than we otherwise 
could how it is that we may have cotton Avorms year after year when 
it is probably' true that very rarely, if ever, does a single moth of this 
species survive the winter within the limits of the United States, 
unless in south Florida and Texas. All immature stages die quickly 
with but little cold. The species appears to pass the winter where 
cotton also lives through and mainly perhaps in the West Indies and 
South America. From these far distant regions the moths fly north- 
ward with each succeeding generation until they overepread the cot- 
ton States and many othei's where cotton does not occur. 

Feeding habits of worms. — For the first few days of their active 
life the young worms feed only on the underside of the leaf on which 
they hatch. They do not eat clear through, but leave the thin upper 
tissue of the leaf uncut — probably partly as a measure of protection. 
These " skinned spots " quickly turn brown and are quite character- 
istic of young leaf wonn work. They are a good guide to follow 
when hunting for young worms. After they have shed their first 
skin, the worms become large and strong enough to eat through the 
leaves and then usually begin to move toward the more tender 
foliage at the top of the plant. Up to this time the young worms 
can hardly be poisoned by any dust method. After they move to 
the top they become one of the easiest leaf-eating caterpillars to 
destroy. They prefer the tops of the plants and the thin blade of 
the leaf, and these are exactly the parts where poison is most easily 
distributed for their destruction. 

The first " ragging " begins only when many worms are about half 
grown — that is, about 5 to 7 days old. After that the rate of destruc- 
tion of the leaves depends upon the number of worms at work. It 
may take a week or only two days to strip a field. In 1911 it was a 
very common matter to hear men tell of first discoA'ering a few worms 
" ragging " their cotton on Saturday afternoon and finding early on 
Monday morning, when they would go out to poison, tha.t there 
wouldn't be enough leaf left to put poison on. Treatment for cotton 
worms must therefore be made just as soon as the first signs of their 
work appear. There may be no time thereafter to send oflF for poison, 
even if ordered by telegraph and shipped by express. The only safe 
way is to be prepared, even before worms appear, with the dusting 
outfit made and some stock of poison kept on hand. • Some illustra- 
tions of cotton worm work are shown in Plates II and III. When 



8 



COTTON WORM OR CATERPILLAR. 



pushed for food the worms commonly destroy all squares, small bolls, 
and even many of those that are fully grown, and gnaw the bark 




Plate 1L— COTTON WORM WORK. 

Fig. I, worms devouring loaf; Ra. L', bolls eaten info and ruined; flg. .3, lint dirty and 
stained. All natural size. (Original.) 



COTTON WORM OR CATERPILLAR. 9 

from the stalk. They may then leave the stripped field in hordes, 
marching for a fresh food supply; hence the name (improperly 
applied) " army worm." 

Generations. — As shown in the account of its life history, the life 
cycle is completed in about three weeks. There are therefore really 
some six or more generations of these worms somewhere on cotton 
during our usual growing season. It is customary for planters to 
speak of that generation which does the first noticed " ragging '' as 
being " the first crop," and the succeeding " crops " are numbered 
accordingly. We usually have three destructive generations in years 
of severe outbreaks. In Alabama, in 1911, the first stripping occurred 
toward the latter part of July. In other fields there was more general 
stripping before the 10th of August. By the middle of the month 
58 counties reported worms. Up to this time the damage might be 
considered local rather than general. From the moths that were 
very numerous between August 10 and 15, tlie next generation was 
expected to and did strip cotton generally during the last 10 days of 
August, and the next generation appeared about the middle of Sep- 
tember. The most favorable and effective time to poison these worms 
is at the time the first worms of each generation move to the tops 
and " ragging " begins, provided a poison like arsenate of lead is 
used that will adhere to the leaves in spite of rains for a sufficiently 
long time to kill practically all worms in the generation as fast as 
they become large enough to eat through the leaves. Generations 
become less clearly defined and the difference in time between the 
first and last members in each becomes greater with each successive 
" crop " of worms. 

Enemies. — The cotton worm has a number of natural enemies, some 
of which are quite important as aids in destroying them. Among 
these are some of the small brown ants, known as " fire ants "; ground 
beetles, wasps, and predaceous bugs; parasitic flies and wasps upon 
the eggs, the worms, or the pupa?; birds, etc. All of these help, but 
even when most effective it is hardly possible for them to prevent the 
multiplication of the worms to a point where it will not require the 
application of poison to save the cotton. 

POISONING COTTON WORMS. 

As has been explained, the feeding habits of these worms are such 
that it is a very easy species to control by simply dusting an arsenical 
poison lightly over the top of the cotton plants. The discovery that 
this could bo done is said to have been made in 1872 by an Ala- 
bamian living near Mobile. At any rate, the use of Paris green for 
this purpose began at about that time, and it was used quite exten- 
sively in 1873, which was such a disastrous year for this State. In 
1879 agents of the United States Department of Agriculture working 
in Alabama made a series of tests of various poisons and established 
the superiority of Paris green among all the materials known at that 
time. Paris green remained the best material known until 1907, when 
powdered arsenate of lead was first produced for special experiments 
with it against the boll weevil. In 1911, therefore, occurred the first 
opportunity for comparing this new material with the more widely 
known Paris green for cotton worms. 
59361°— H. Doc. 917, 62-2 2 



10 COTTON WOEM OR CATERPILLAR. 

Powdered arsenate of lead. — This is by far the best poison for the 
control of the cotton worm. There is a " paste " form made which 
can not be used except for spraying. The other form known as " pow- 
dered " arsenate of lead is a very fine white powder having about 
one-half the amount of arsenic in it that is in Paris green, and should 
therefore be used at least twice as strong as we use Paris green to 
secure the same killing power. It never burns, even if applied to 
foliage in heav}^ doses, and sticks to the leaves very well in spite of 
rains. It seems to be so very fine that it gets into the small depres- 
sions on the leaves and the water runs over it. AVe therefore advise 
a dose of 3 pounds of powdered arsenate of lead per acre for average 
cotton when this can be secured in place of Paris green. No flour or 
any other material is needed in this case. Closely woven flour-bag 
cloth or unbleached sheeting should be used with this very fine mate- 
rial. It is easier to apply this arsenate of lead evenly than it is Paris 
green and flour. 

Paris green. — For nearly 40 years this has been the best poison 
known for the cotton worm, and for this reason is still in demand 
among those who have used it or who have not yet tried the arsenate 
of lead. 

Other poisons. — No other poisons now on the market need be con- 
sidered. Arsenite of zinc might have value, but has not yet been 
tested on cotton. London jourple is certain to burn badl^y, and white 
arsenic is sure to kill every leaf it is put on. Do not waste time and 
opportunity fooling with untried or unreliable or fake remedies. 

Comparisons. — It is a well-known fact that Paris green is very 
likely to bum cotton foliage in spots even where carefully distributed 
and is certain to do so where at all carelessly put out. Many planters 
know also that it has the effect of checking the setting of fruit when 
applied to young cotton even where burning of foliage is not ap- 
parent. This is a matter for very serious consideration. We can not 
advise the application of Paris green to any cotton until after the crop 
of bolls is well made and nearly mature, if it be possible to secure the 
arsenate of lead in its place. 

Furthermore, it is well Iniown that Paris green, even when applied 
with flour, is readily washed off the plants by rains and even by heavy 
dews, so that the effectiveness of an application may be entirely 
destro3^ed within 24 hours. In many places there is also a strong 
prejudice against Paris green because of the fact that it is likely to 
cause sores on the men and mules using it for any considerable length 
of time. In some cases in 1911 this resulted in the positive refusal 
of workmen to continue handling Paris green. The trouble on the 
plant, workmen, and animals is that Paris green contains four or five 
times as much water soluble arsenic as does the arsenate of lead, 
and this is tlie constituent that burns. 

On the other hand, powdered arsenate of lead even when applied 
as heavily as 10 pounds or more of the undiluted poison to the acre 
does not burn foliage and does not check the setting of fruit. This 
material ahheres to the foliage five times as long as does Paris green. 
It therefore gives the plants all the advantage of continuous protec- 
tion and is economical to use because fewer applications are required. 
Many hundred thousand pounds of this material were used in 1911 
without a single record of its causing sores on men or mules. There- 
fore, while costing slightly more per acre for the poison and requiring 



COTTON WORM OR CATERPILLAR. 11 

the application of more powder to the acre than is the case with Paris 
green, the real saving- in the crop and the safety with which it may 
be applied makes this material tlie best that we know for application, 
particularly to cotton before the crop is nearly matnred, at which 
time Paris green could be used if already on hand. Never use white 
arsenic or London purple on cotton. 

Paris-green treatment is cheaper than that with arsenate of lead 
if we consider only the first cost of the materials used in each appli- 
cation, but real economy is measured by the saving in crop obtained 
as compared with the total cost of protecting it to the end. On this 
basis it may be far more expensive than the lead for an}' one or all 
of several reasons. A heavy rain falling within 21 hours after the 
ajDi^lication will so wash Paris green from the plants that it may b© 
ahnost wholly ineffective and the work must, therefore be done over 
at once. That application was therefore entirelv wasted. Again, if 
through its effect on the plant in checking fruiting, there results the 
throwing oif or prevention of making of even one boll on every 10 
stalks on the average, then it will cost more than the arsenate of 
lead treatment. The effect would surely be much greater than this. 

Analysis^ tcith quotation of price. — The large stocks of both Paris 
green and arsenate of lead in Alabama include the ]Droducts of sev- 
eral different manufacturers. In all cases where considering the pur- 
chase of either poison the buyer should insist upon being given a 
statement of the guaranteed analysis of the poison, together with the 
quotation as to its cost, just as he would do with a fertilizer, like acid 
phosphate. In this way he can best detennine where he can get the 
maximum of insect-killing value at the minimum cost. Arsenate of 
lead should contain from 23 to 33 per cent of arsenious oxide, and the 
cost may vary accordingly. Paris green should have 50 to 56 per 
cent arsenious oxide. In case of extreme shoi-tage of poison it may 
be necessary to make use of what stock is available of what is known 
as " Paris-green residue," which is a low-grade product not ordina- 
rily used as an insecticide. In many localities planters may combine 
their orders and secure the benefit of lower prices and freight rates. 
Neither poison loses strength and th.Qj may be kept for years if 
simply kept very dry. 

INFORMATION ABOUT USING POISONS. 

Arsenate of lead. — 'Wiih powdered arsenate of lead we make it the 
general rule to apply at each application as many pounds per acre as 
the cotton is feet in height. These limits can be drawn in somewhat, 
as 2 pounds will be needed even on small cotton, and that 6 feet high 
could be fairly well protected with 4 or 5 pounds. The cost of the 
poison will probably average close to 25 cents per pound for 25 to 33 
per cent powdered arsenate of lead. Multiply this by the number of 
pounds to be used per acre and add about 5 or 10 cents for the labor 
of application to get at the cost of treatment. 

Pans green. — This material can not be applied with any assurance 
for the safety of the plant stronger than 1 to 14^ pounds per acre. 
With this we must use some 2 pounds of flour for every pound of 
Paris green to be applied. The poison will cost also about 25 cents 
per pound in small lots. To this add the cost of flour and labor. 

Number of applications nseded. — This depends on which poison 
you decide to use. With the arsenate of lead it was found in 1911 



12 COTTON WORM OR CATERPILLAR. 

that one good dusting applied at the beginning of each " crop •■ of 
Avorms would give the cotton full protection from the entire genera- 
tion. This material sticks in spite of dews and rains, so that it re- 
mains effective for the last as well as the first hatched worms in each 
generation. Experience has shown, however, that even with this a 
new application must be made at the beginning of each " crop " of 
worms. Three treatments with arsenate of lead may be expected to 
carry the crop through the worst part of even the most serious out- 
breaks. The stock of poison needed may be closely estimated and pur- 
chased at the beginning of the season. 

With Paris green so much depends upon the state of the weather 
that it is simply impossible to tell Avith nny certainty how many ap- 
plications may be required. In 1911 fields were seen where three and 
four applications had been made for o?ie " crop " of worms, and the 
plants were in bad shape then. It will not be safe to count on having 
to make less than five applications of this material, and even then the 
jDrotection given the crop may be less complete and continuous than 
with the other poison. 

'When to apply /JC»^S6>?^.— Watch your cotton closely and frequently 
for the first signs of worm work. These usually occur in the low wet 
places where the cotton is rank. The cotton worm feeds on no plant 
but cotton and few other worms do a similar work in " ragging " the 
leaves or stripping the plants. The " first crop " of worms will 
usuallj^ appear in spots through the field and not attacking all parts 
uniformly. The worms should be poisoned at once whenever and 
wherever they are found to be " ragging " the tops of the plants. At 
the time of appearance -of the " first crop " it will not pay usually to 
treat the whole field unless the worms are scattered through it. If 
the " first crop " appears in considerable numbers during the last of 
Jul}" or first of August, and if the seasonisrather wet and cotton rank 
and thrift}", then there is great likelihood of extensive damage from 
the " second crop " which may appear in from 10 to 15 days after the 
worms of the first crop spin up. Every preparation should be made 
in advance when such conditions occur so that the whole cotton crop 
may be treated without a single hour of avoidable delay. Have the 
dust poles and bags ready and the stock of poison on hand. Such 
preparation is essential to the best success in controlling these worms. 
One dollar expended in poisoning caterj^illars during August may 
save from $10 to $50 loss in the crop. It pays to kill the worms early. 
(SeePl. Ill, figs, lands.) 

Sources of poison supphj. — These arsenical poisons are manufac- 
tured entirely outside of the cotton States. The addresses of manu- 
facturers and wholesale dealers can be obtained from a local druggist 
or by writing to the State experiment station and quotations on large 
quantities thus gotten at bottom prices. Most buyers, however, will 
not prepare early enough to allow shipments from long distances to 
reach them in time to save their cotton. They depend upon reaching 
a nearby center of supply. In each of the larger cities of Alabama 
ma}^ be found one or more firms handling these poisons. They should 
advertise their stock during every outbreak of worms so that farmers 
may know where to get their poison with least delay. 

Place your order early. You can not expect a dealer to assume all 
the responsibilit}^ and carry a stock large enough to cover all possible 
demands in his territory. Bankers, merchants, oil-mill men and 



COTTON WORM OR CATERPILLAR. 



13 



fertilizer men especially should make it certain that an adequate 
supply of poison can be had by their customers without delay and 




.^ 



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•'^.>fV3^'^:^,4 



Plate ITT.— PROTECTING COTTON FOLIAGE. 

Fig. 1, on left, foliage saved Dy poisoning; on right, cotton stripped by worms and crop 
cut 8 per cent. Fig. 2, very ranlt cotton protected through season by three dustings with 
arsenate of lead, yielding nearly 2 bales per acre. (Original.) 



14 



COTTON WORM OR CATERPILLAR. 



every assurance given the farmer that he can get this poison at very 
reasonable cost. Those who have ah'eady " advanced " on the crojD 
should insist that their customers apply the poison for the j^rotectioii 
of their common interests. 





I'LATE IV.— APPARATUS FOU DESTROYING WORMS. 

Fig. 1, largo scale work pconomioally done ; fig. 2, trap lantern utilizing washtub — a 
shallow pan is even better ; fig. 3, dusting outfit of good type. 

J/ethods of application. — Either of these poisons can be applied 
as a spray or a dust. Few cotton planters, however, have equipment 
for the spraying and that method of application requires slower work 



COTTON WORM OR CATERPILLAS. 15 

than the dusting. Under the subject " Feeding liabits " we have 
shown why a dust application is unusually simple and effective for 
the cotton worm and that is why we recommend the dust treatment. 

THE DUSTING TREATMENT. 

The simplest possible method for destroying cotton worms is to 
apph' a dry poison like Paris green, or better, powdered arsenate of 
lead, dusted through bags carried at the ends of a pole or piece of 
narrow board, by a man riding a mule. This covers two rows at a 
time and 15 to 20 acres can be treated by one man in a day. On 
moonlight nights the work might probably be continued in cases of 
emergency. Somewhat less uniform but more rapid work can be 
done by making the board long enough to cover four rows, or better, 
three middles. Two bags should be used on each side, if the board is 
more than 10 feet long, to give better distribution of the dust. The 
spring in the longer boards makes it unnecessary to jar them. They 
may simply be held firmly on the front of the saddle and the mule 
ridden at a trot, leaving a cloud of dust behind. Where several men 
are working, they should ride abreast. 

The out-fit. — To make the dusting outfit, take a piece of 1 b}^ 3 or 
1 by 4 inch board and cut it about 18 inches longer than the distance 
at which the cotton rows are planted. Also cut four blocks off of the 
same board each about 4 inches long. In each end of the main board 
bore a 1-inch, or larger, hole, through which the poison can be poured 
into the finished bags. These holes may be closed with plugs or 
stoppers after the poison has been introduced. Nail the four blocks on 
the underside of the board, one at each end and the others about 16 
inches from the ends. These blocks thus form the ends of the bags. 
The long board may be cut down in the middle to a width that is easy 
to hold in the hands and so as to remove unnecessary weight. (See 
PI. IV, fig. 3.) For the bags to be used with arsenate of lead or Paris 
green with two parts of flour, such a cloth as unbleached domestic 
or sheeting answers well. This cloth will distribute about 3 pounds 
per acre. This jjhould be folded over, stretched, and tacked closely 
to the side of the board, then around the blocks and to the board on 
the other side. The amount of poison distributed will depend upon 
the tightness of weave of the cloth and the jarring given the pole. 
If, with rather continuous jarring, not enough poison is being dis- 
tributed, simply use more open cloth for the bags. Old flour bags 
may be used if on hand. Where it is desired to put out 5 or G pounds 
per acre, use double cheesecloth for the bags. 

Witii Paris green a closer woven cloth may be needed and '' 8-ounce 
duck" may be used for light applications of the pure poison without 
any flour. It is desirable to use about 2 pounds of flour with each 
pound of Paris green to increase its sticking to the leaves, and flour 
bags or sheeting may then be used. Do not try to use old " oat sacks " 
and think that the work can be done economically. 

Suggestions regarding applications. — The best air condition for 
applying a dust is found when it is still. The worms feed principally 
at night and in the early morning before they have difficulty in get- 
ting enough food. After that they may feed during bright days and 
are always more generally active during cloudy days. Dust poisons 
applied toward evening are therefore likely to be on the plant in 



16 COTTON WORM OR CATERPILLAR. 

their maximum strength while the worms are feeding most actively. 
DeAv forming on the poison helps to fix it in place, but very heavy 
dews that drip from the plants may wash off a large part of the Paris 
green within a short time even without rains. ^\lien dusting while 
dew is on it is very important to avoid touching the dust bags to the 
plants, since if the cloth becomes wet the dust can not pass through it. 
NeA'er attempt poisoning during or just before a rain with Paris 
green. Arsenate of lead can be put on with assurance that it will stay 
if it only has time to once dry on the leaves. There is a much greater 
safe-working margin with it than with Paris green in the dosage that 
can be safely used, the length of time that it can be used before the 
worms will get to it, and the sureness of the protection obtainable in 
showery weather. 

Keeping track of weiglit. — A spring balance weighing up to 20 
pounds is a convenient help in keeping close track of the amount of 
poison being put out. Weigh the whole outfit, pole. bag. and poison, 
after the poison has been put in and it is ready for the rider. After 
half an acre (an acre is 70 by 70 yards) or any known area is covered 
weigh again. The difference in weight shows just exactly how much 
poison has been put out on that area, and if too much is gone for the 
rate desired, either use heavier cloth for the bags, add another cover- 
ing of thin cloth, or try lighter jarring. If Paris gi-een is being used 
the proportion of flour to poison may be increased. If too little 
poison is going out, jar more heavily or use a lighter weight or more 
open cloth. This means economical treatment. 



IS THERE DANGER IN USING POISONS 



This is one of the questions most commonly asked by those who have 
never yet used any. Fortunately the danger is far more imaginary 
than real. Both fear and danger in the use of poisons for the cotton 
worm or other insects arise almost entirely from ignorance as to their 
nature and effects. Only when very carelessly handled is there any 
real danger in using either Paris green or powdered arsenate of lead. 
Of course, both are strong stomach poisons, and their value in pro- 
tecting cotton from the worms lies in this fact. They are not at all 
likely to produce any serious effects unless taken into the stomach of 
man or beast in very appreciable quantities. There is no real danger 
from getting either on the skin. It is true, however, that Paris green 
is liable to cause rather bad sores on men and mules where they are 
working Avith it constantly for several days in succession. This is 
due to the same quality of Paris green that makes it bad to use on 
thrifty growing cotton. It usually contains about 3 per cent of arsenic 
in a form that is soluble in water or in perspiration. This causes the 
burning of foliage and also the sores on men and mules. This, how- 
ever, never happens with the arsenate of lead. The only real danger 
to stock lies in allowing animals to get into freshly poisoned fields and 
to feed therein for several hours at a time. One case is known to me 
where cotton was planted on a steep slope nearly encircling a small 
pool into which it drained. No stream flowed through or from this 
}iool, but it was used as a water hole for some farm stock. Very soon 
after the cotton was very heavily poisoned Avith Paris green a heaA'y 
shower washed it from the ])lants and down the steep hillside into the 
water hole, where it was held and concentrated to such an extent that 



COTTON WORM OR CATERPILLAR. 17 

some of the animals drinking there were poisoned. But these condi- 
tions would not occur again in many thousands of cases. Every re- 
port of the killing of men and of mules that could be investigated in 
1011, with only one exception, were found to be mere "rumors" or 
mistakes. In that case an animal broke into a freshly poisoned field 
and fed all night, so that it got a fatal dose. There is very rarely 
need to muzzle mules to protect them during an application. There is 
no chance whatever of " poisoning the soil," and no danger in letting 
stock feed, even where arsenate of lead has been used, after a month's 
time. There is no danger to stock drinking from running streams 
passing through treated fields nor to cotton pickers at picking time. 
Poultry may possibly be killed if allowed to feed extensively on 
worms dying from poison. A few simple, sensible precautions should, 
however, be observed. 

Precautions. — Keep all poison so marked in a plain manner and 
store it in a dry place out of the reach of children and farm animals. 
Fill cuts or scratches with vaseline or some grease and tie a cloth over 
it or wear gloves. Work toward the wind if it is l^lowing across the 
field. Tie a cloth or handkerchief over the mouth and nose if 
obliged to ride with the cloud of dust to any great' extent. Clear 
the throat occasionally and spit out the accuinulation instead of 
swallowing it. If using Paris green, brush off or wash off mules and 
men after the day's work. If the work extends over several days, 
change men and mules to give each a rest, for it is hard work when 
followed constantly. Shut up poultry for two or three days when 
cotton, Avhere the}^ might spend most of their time, has just been 
treated. In case of accidental poisoning, produce vomiting as 
quickW as possible by limning a finger down in the throat. Hot 
milk or mustard water will usually start it. Then give milk, raw 
whites of eggs, or magnesia (magnesium oxide), a rounding tea- 
spoonful in a glass of milk. Get a doctor at once. 

LIGHT TRAPS. 

Cotton worm moths are readily attracted to lights and may be 
trapped in large numbers, thus preventing many worms, but at be^t 
this can not be considered as a substitute for poisoning. It will be 
helpfid to test the emergence of the moths in this way and thus to 
know just when to begin the applications of the arsenate of lead. 

A lantern or light trap (see PI. IV, fig. 2) may be easily and 
cheaply made, as follows : Arrange in some way by using a box, 
barrel, or stake with a board on top. to raise the trap a foot or two 
above the tops of the cotton plants. Place on this a shallow pan or 
a tub containing an inch of water, Avith just enough kerosene or coal 
oil to form a film over its surface to kill the insects that may fall 
into it. In the middle of the pan set an ordinary lantern. Let this 
burn through the night to attract the moths which may come from 
some little distance to it. Xo one knows how far this will attract, 
them. Doubtless much depends upon the brightness of the light or 
the darkness of the night. There is no danger of drawing moths to 
the field without catching them and thus decreasing their injurious- 
ness. The whole effect is like that of pouring Avater. It flows only 
as you lower the surface at some point. Such lights will attract 



18 COTTON WORM OR CATERPILLAR. 

many moths and other insects beside the cotton moth, and the oil will 
so change the appearance of those caught that one must know the 
moth well by size, shape, and wing markings to tell them. Bonfires 
do less good than lanterns, as the heat i-epels the moths before they 
get singed. Flying against the lantern, they simply drop into the 
oil and water. 

DOES IT I'AY TO FIGHT COTTON WORMS? 

It seems almost ridiculous to ask such a question, and yet from the 
fact that a very large majority of cotton planters will sit quietly by 
and see their crop eaten up and their season's w^ork largely destroyed, 
without being willing to spend from $1 to $3 per acre to save it, it 
appears that the average man does not yet believe that it will really 
pay him to make this fight. Let us therefore consider the question 
a fair one and figure out the answer. 

On the average field there are at least 5,000 cotton plants, and with 
most varieties it does not take over 80 bolls to make a pound of seed 
cotton. One boll to the plant therefore means about 60 pounds of 
seed cotton, containing about 20 pounds of lint and 40 pounds of 
seed. At the price of the 1911-12 season this lint is therefore worth 
over $2 and the seed about 50 cents more, giving us a total value of 
over $2.50 for each boll per stalk per acre. Now", an average applica- 
tion of arsenate of lead will cost about 75 cents for the poison and not 
over 15 cents per acre for its application, a total of 90 cents per acre 
for each application, which is only about one-third of the minimum 
saving in the crop if by the treatment we insure the opening of but 
one more boll per stalk than would have opened otherwise. One boll 
per stalk will pay for the three complete poisonings, which is the 
maximum that may be required for the three " crops of Avorms " 
which may appear before the cotton is ready to open. Will it pay? 
AMio does not believe that by saving the foliage on his cotton from 
the worms he can save more than one boll per stalk? In 1911 in 
cotton fields thought to be so nearly mature that the worms would do 
them no harm whatever, few escaped without the loss of two or three 
bolls per stalk. In 1911 the average damage throughout Alabama 
could not have been less than 10 per cent of the crop gathered, or 
somewhere between 150,000 and 200,000 bales for the State. The 
cotton-worm tax here last year was probably not less than $10,000,000, 
and would have been far more but for the fortunate fact that in that 
year between 90 and 95 per cent of our crop was " made " before the 
1st of August. Very little increase took place after that time. Our 
crop of 1912 averages all of three weeks later than that of 1911. 
The possibility of injury to the 1912 crop is therefore correspondingly 
greater. 

COTTON WORM VERSUS BOLL WEEVIL. 

We have here a peculiar case of natural conflict between two ex- 
clusive cotton pests attacking normally entirely ditferent parts of the 
plants. The boll Aveevil depends absolutely upon the presence of 
squares and bolls for opportunity to reproduce. When the fields 
are stripped clean by the cotton worm nature demonstrates to us on 
a large scale the value of a practically complete destruction of cotton 
at an early date as a measure of control for the boll weevil. In seasons 



COTTON WORM OR CATERPILLAR. 19 

of general cotton worm occurrence the late developed weevils are so 
reduced in numbers that the cotton crop of the following year is 
usually but lightly infested until an unusually late date the following 
year, with consequent advantage to the crop. One cotton pest — the 
cotton worm — thus serves to control the other — the boll Aveevil, The 
cotton worm may be considered as a friend by the planter in weevil 
territory when it occurs after the bolls are all practically fulI-gTown, 
because of this effect on the weevil. Whenever the two pests occur 
together before cotton has reached this stage poison should be used 
for the cotton worm, as only thereby can the largest possible crop be 
secured. As a general rule in Alabama cotton worms should be poi- 
soned everywhere until the 10th to loth of September. Cotton should 
be picked out as promptly as possible after it opens, and then the 
planter may complete, by deeply plowing under or by plowing out and 
burning the stalks, the control of the boll weevil that may be begun 
by the cotton worm. 

COTTON WORM APPEARANCE, ]!>12. 

The first appearance of cotton worms in the United States this 
season was, as usual, in the southern extremity of Texas. This was 
noticed about the 1st of May. The third generation in that section 
became mature about the middle of July. 

During the first week in June a number of moths were taken at 
lights in Mobile, Ala. These may possibly have flown across the 
water from some of the West Indian Islands. Cotton worms were 
found in, or reliable reports of their occurrence received from, Ala- 
bama counties on the following dates: Mobile, June 6; Conecuh, June 
21 ; Autauga, July 12 ; Pike, July 18 ; Geneva, Covington, and Mont- 
gomery, July 19 ; Butler, July 22 ; Perry, July 21, etc. 

On July 21 Prof. K. W. Harned^ of Mississippi, reported cotton 
w^orms as occurring in Lowndes, Monroe, Oktibbeha, and Noxubee 
Counties, in that State. We are now having in coincidence the con- 
ditions that have occurred whenever there have been general out- 
breaks of the cotton worm, and there is little likelihood that we shall 
escape this year. At the present time the prospect is for fully as 
extensive an outbreak, and for even more serious injury to the crop 
than occurred in 1911. We can only hope that by last year's experi- 
ence we may be more promptly and fully prepared, so that Ave m.ay 
make the fight tliis year more general, more economical, and more 
effective than any such fight has ever been before. It will pay to 
poison even as the bolls are opening to keep the lint free from trash 
and staining, which is frequently a serious matter, as suggested in 
the view in Plate II, fig. 3. 

It has been so clearly and abundantly proven that cotton can be 
completely protected from this pest at very low cost compared with 
the loss that is bound to be sustained if the cotton womis are allowed 
to strip the fields at any time before the crop is fully matured, that no 
one should hesitate to undertake to fight against the cotton wonn. 

o 







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